some customer receive a white page

I don't know why, but some of my customer who register for my event receive a white page as result of registration.
One of my customer give me the link to the page :
www.day.motoraddict.be/accueil/registrat...tion_code=9l1lPhRV85
And effectively, it's a white page.
Could you help to solve this problem ?
Regards,
Olivier

Hi Oliver

Please submit a support ticket sending us admin and FTP account of your site. We will check and solve the issue for you.

Maybe you should download latest version and upgrade to your site first 1

Tuan

Hi, it's already upgraded.
For 10 customers, 4 have this problem.
I will submit the ticket now.
Regards,
Olivier

Hi Olivier

I upgraded your site to latest version of the extension and It seems the error is gone. Could you please check it for all customers again ?

Tuan